Wireless communication standards whose communication use a frequency band same as that of a television broadcast being a licensed business and can be operated with no such a license, have been investigated. In these standards, a television broadcaster is a primary user, and only when a licensed frequency band of the primary user is not used, a secondary user is allowed to operate a wireless communication in the frequency band (licensed frequency band which is not used=TV white space; TVWS).
Wireless devices (an access point device and a terminal, for example) used under this environment find, when a power supply thereof is turned on, all of available frequency bands (channels) with no TV signals existed therein through sensing, and start an operation in any of the available frequency bands, for example. It can be considered that such the sensing requires an enormous amount of time since a frequency band to be a target of sensing is very wide.
Therefore, it can be considered that an information transmission station which keeps transmitting information of available channels all the time, as a broadcast, is provided and operated. Thereby, each of the wireless devices only can receive the information, and can be released from an enormous amount of burden such as the sensing. Meanwhile, since an amount of information transmitted by such an information transmission station is considered to be very large, it can be considered that the information transmission station preferably performs efficient information transmission which is easy to use for the wireless devices.